It started when Eric Holder’s Department of Justice essentially backed down in the face of marijuana legalization by popular vote in both Colorado and Washington state, saying it would not challenge the new state laws defying federal statute, as long as the states create “tightly regulated” markets that address eight federal “enforcement priorities.”

Then, seven national law enforcement agencies threw a hissy-fit. They sent an angry letter to the DOJ complaining about the enforcement decision. Their main concern?

“The failure of the Department of Justice to challenge state policies that clearly contradict Federal law is both unacceptable and unprecedented. The failure of the Federal government to act in this matter is an open invitation to other states to legalize marijuana in defiance of federal law.” [Emphasis original]

Huffington Post columnist Ryan Grim grasped the significance of the law enforcement panic attack, “If there had been doubt about how meaningful Holder’s move was, the fury reflected in the police response eliminates it,” he wrote.

That very same day, Kentucky Agricultural Commissioner James Comer proved the cops’ fears legitimate, but with a twist. He said the DOJ retreat gives Kentucky the green light to move forward with hemp cultivation. According to an Ag Commission press release, “In a landmark ruling, the Justice Department has reversed its policy and will honor state laws regarding regulated marijuana sales. Kentucky Agriculture Commissioner James Comer, a national leader in the industrial hemp movement, believes the ruling includes the production of industrial hemp.”

Comer began pushing for industrial hemp legalization within a month of taking office in 2011. His efforts paid off when the Kentucky legislature passed SB50 last March. The law legalizes industrial hemp farming in the Bluegrass State, but the federal government must first lift its ban before farmers can begin planting the crop. Comer said the Department of Justice announcement effectively lifted the federal ban.

“It’s about time! This is a major victory for Kentucky’s farmers and for all Kentuckians. Two years ago, the Obama administration would not even discuss the legalization of industrial hemp,” Comer said. “But through a bi-partisan coalition of Kentucky leaders, we forced their hand. We refused to listen to the naysayers, passed a hemp bill by a landslide, and our state is now on the forefront of an exciting new industry. That’s called leadership.”

The dominoes actually began their cascade back back in the 90s when California voters approved Proposition 215 legalizing medical marijuana. Since then, 21 have states jumped on the medicinal cannabis train, despite a Supreme Court opinion asserting the feds can indeed prohibited it across the United States. The dominoes continued tumbling last fall when Colorado and Washington voters rejected federal prohibition and chose to legalize marijuana for recreational use within their states. And now the Department of Justice decision not to challenge the will of the people in Colorado and Washington has sent the falling dominoes down a completely new path.

Nullification works.

And it tends to snowball.

Once a single state takes a stand, others become emboldened and follow suit. We’ve seen this play out vividly in the marijuana issue over the last 15 years, and now with expansion in to industrial hemp. We will likely see this phenomenon repeat as states stand up to challenge other unconstitutional acts like indefinite detention, Obamacare and violations of the Second Amendment.